CN1062542C

CN1062542C - Composite ceramics and production thereof

Info

Publication number: CN1062542C
Application number: CN95111718A
Authority: CN
Inventors: 王佩玲; 王浩; 孙维莹; 庄汉锐; 严东生
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 1995-08-04
Filing date: 1995-08-04
Publication date: 2001-02-28
Anticipated expiration: 2015-08-04
Also published as: CN1142478A

Abstract

The present invention relates to a sialon composite ceramic which belongs to a silicon nitride base material and a making method thereof. The values of m and n in the general formula of alpha' of Y<m/3>Si<12-(m+n)>Al<m+n>O<n>N<16-n> are used as main parameters for designing the alpha' and beta' content of the main crystal phase of the sialon composite ceramic, wherein when m equals to 0.3 and n equals to 1.0, the ratio of alpha' to beta' approaches to 50:50, and the YAG content of the crystal boundary phase is 9% the weight of the main crystal phase. The making method is the general ceramic making method which comprises: raw materials are compounded and treated by uniaxial forming at 20MPa and cold isostatic pressing forming at 200MPa, biscuits are sintered in a pressureless mode at 1 atm at the temperature of 1800 DEG C which is preserved for 2 hours, or then sintered at the high nitrogen pressure of 1.5MPa and the temperature of 1900 to 2000 DEG C for 1.5 to 3.0 hours, and the embedding powder is Si3N4, AlN and BN, with the ratio of 6:3:1(wt%). The made composite ceramic has the strength at the high temperature of 1350 DEG C of larger than 500MPa, and the highest strength can reach 715MPa.

Description

Composite ceramics and preparation method

A kind of high strength with excellent high mechanical property of not having pressure and the preparation of high nitrogen pressure sintering process of the foot that the present invention relates to, grand (Sialon) complex phase ceramic of high rigidity match belongs to the silicon nitride-based material field.

Sialon is Si ₃N ₄Sosoloid, Si is at first proposed in 1972 by people such as K.H.Jack ₃N ₄α-Si is arranged ₃N ₄And β-Si ₃N ₄Two kinds of variant are called α-Sialon and beta-Sialon with their isostructural sosoloid, with Si ₃N ₄The same, the grain morphology and the performance of these sosoloid have their own characteristics each, and be each has something to recommend him.For example: the α match is swelled and is had high rigidity and good heat-shock resistance, the β match is swelled and is had high intensity and high fracture toughness property, grand and the grand Sialon complex phase ceramic of forming of β match can be learnt from other's strong points to offset one's weaknesses both and formed and have high rigidity concurrently with α match, and the Sialon complex phase ceramic of high strength (especially intensity under the high temperature) is arranged, be the purpose that the ceramist pursues for it always.

Yet, because Si ₃N ₄Material is the very strong material of covalent linkage, thereby causes being difficult to sintering densification, often adds metal oxide such as La in sintering process ₂O ₃, Y ₂O ₃, Al ₂O ₃As additive, and make ceramic densifying by the approach of liquid phase sintering.It's a pity that liquid phase is present in the crystal boundary of pottery with the form of glassy phase in process of cooling, influenced ceramic mechanical behavior under high temperature and limited range of application thereby the glassy phase softening temperature is low.

The objective of the invention is to use existing Y, Si, Al, O, N quinary system facies relationship knowledge, seek out component zone, do not press sintering process to prepare the composite ceramics of excellent property with having pressure and high nitrogen with good sintering character.

The objective of the invention is by with high-melting-point YAG (Y ₃Al ₅O ₁₂) be the crystal boundary phase, utilize that the grand and β match of α match is grand to have high rigidity and high-intensity advantage respectively and do not press and the Sialon complex phase ceramic of high nitrogen pressure technology preparation implements to have.

Specifically:

(1) with the grand general formula Y of α match _M/3Si _12-(m+n)Al _M+nO _nN _16-nIn the significant parameter of m, n value and β match grand content grand as design composite ceramics principal crystalline phase α match, work as m=0.3, it is grand that n=1.0 obtains the α match: the grand ratio of β match equals 50: 50, and fluctuation range is 40: 60.

(2) α match coking property grand and the β composite ceramics depends on YAG (Y in the original component ₃Al ₅O ₁₂) content, the content that the present invention controls YAG is 9% of principal crystalline phase weight, YAG is the crystal boundary phase.

(3) starting powder Si ₃N ₄Be the UBE-10 of Ube product company production newly, AlN, Al ₂O ₃, Y ₂O ₃Purity be 99.9%, average grain size 1-2 μ m.After above-mentioned (1), the weighing of (2) composition proportioning, at Al ₂O ₃Be dispersion medium with the dehydrated alcohol in the ball grinding cylinder, Si ₃N ₄Ball is that ball-milling medium mixed 24 hours, take out the slurry oven dry after, sieve through 75 eye mesh screens, at 20MPa uniaxial tension compacted under after the 200MPa isostatic cool pressing is made biscuit.

(4) biscuit is at 1800 ℃ of 1 normal atmosphere N ₂Pressureless sintering under the air-flow is incubated 2 hours, and it is Si that powder is buried in pressureless sintering ₃N ₄: A1N: BN=6: 3: 1 (wt%) or depressing under 1900-2000 ℃ of temperature 1.5-3.0 hour sintering of insulation at the high nitrogen of 1.5MPa again after the pressureless sintering.

(5) burn till sample all at 1350 ℃ of logical N ₂24 hours crystallization of thermal treatment are handled under the condition.

Advantage of the present invention is:

(1) the α match is grand in the principal crystalline phase: the β match swells=50: 50, and fluctuation range is 40: 60, and the agglomerating complex phase ceramic has high strength and high rigidity concurrently.

(2) owing to being the crystal boundary phase, so material also has excellent high-temperature mechanical property (seeing embodiment 1-5 for details) with high-melting-point YAG.

(3) can help suitability for industrialized production there not being the Sialon complex phase ceramic that obtains densification under pressure and the high nitrogen compression technology condition.

Embodiment 1

Si with the product company production newly of japanese character portion ₃N ₄(UBE-10) be Si ₃N ₄Raw material, AlN, Al ₂O ₃, Y ₂O ₃The purity of powder is 99.9%, average particle size particle size 1-2 μ m, and consider Si ₃N ₄With the oxygen level of nitrogenous particle surfaces such as AIN, press m=0.3, n=1.0, YAG weight is that 9% of principal crystalline phase weight is prepared burden, biscuit is at 1800 ℃, under 1 normal atmosphere flowing nitrogen, pressureless sintering 2 hours, burying powder is Si ₃N ₄: AIN: BN=6: 3: 1 (wt%), burn till behind the sample in 1350 ℃ of logical N ₂Following 24 hours crystallization of condition are handled.The room temperature strength of sample is 612MPa, and fracture toughness property is 3.9 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1594, the intensity in the time of its 1000 ℃ is 595MPa, the intensity in the time of 1350 ℃ is 500MPa.

Embodiment 2

Adopt raw material in high nitrogen pressure stove the sintered sample identical with embodiment 1, at first under 1800 ℃ of 1 normal atmosphere flowing nitrogens, be incubated 2h, depress with 1900 ℃ of insulations 15 hours at the high nitrogen of 1.5MPa then, bury powder with embodiment 1, the room temperature strength of sample is 840MPa, and fracture toughness property is 6.1 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1820, the intensity in the time of its 1000 ℃ is 740MPa, the intensity in the time of 1350 ℃ is 620MPa.

Embodiment 3

Adopt raw material in high nitrogen pressure stove the sintered sample identical with embodiment 1, at first under 1 normal atmosphere flowing nitrogen, be incubated 2h with 1800 ℃, depress with 1900 ℃ of insulations 3.0 hours at the high nitrogen of 1.5MPa then, bury powder with embodiment 1, the room temperature strength of sample is 890MPa, and fracture toughness property is 6.9 (MPam ^1/2), Vickers' hardness (H-V ₁₀) be 1850, the intensity in the time of its 1000 ℃ is 780MPa, the intensity in the time of 1350 ℃ is 660MPa.

Embodiment 4

Adopt raw material in high nitrogen pressure stove the sintered sample identical with embodiment 1, at first under 1 normal atmosphere flowing nitrogen, be incubated 2h with 1800 ℃, depress with 1950 ℃ of insulations 1.5 hours at the high nitrogen of 1.5MPa then, bury powder with embodiment 1, the room temperature strength of sample is 860MPa, and fracture toughness property is 6.5 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1820, the intensity in the time of its 1000 ℃ is 775MPa, the intensity in the time of 1350 ℃ is 650MPa.

Embodiment 5

Adopt raw material in high nitrogen pressure stove the sintered sample identical with embodiment 1, at first under 1 normal atmosphere flowing nitrogen, be incubated 2h, depress with 2000 ℃ of insulations 15 hours at the high nitrogen of 1.5MPa then, bury powder with embodiment 1 with 1800 ℃, the room temperature strength of sample is 925MPa, and fracture toughness property is 7.2 (MPam ^1/2), Vickers' hardness (HV ₁₀) be 1884, the intensity in the time of its 1000 ℃ is 830MPa, the intensity in the time of 1350 ℃ is 715MPa.

Claims

1. a composite ceramics is made up of Y, Si, Al, O, N quinary system, it is characterized in that

(1) with the grand general formula Y of α match _M/3Si _12-(m+n)Al _M+nO _nN _16-nIn the significant parameter of m, n value and β match grand content grand as design composite ceramics principal crystalline phase α match;

(2) m=0.3, during n=1.0, the grand ratio of the grand β match of α match equals 50: 50, and fluctuation range is 40: 60;

(3) crystal boundary phase YAG (Y ₃Al ₅O ₁₂) content be 9% of principal crystalline phase weight;

(4) starting powder Si ₃N ₄Be the UBE-10 of Ube product company production newly, AlN, Al ₂O ₃, Y ₂O ₃Purity be 99.9%, average grain size 1-2 μ m.

2. by the preparation method of the described composite ceramics of claim 1, it is characterized in that:

(1) grand in principal crystalline phase α match: the grand ratio of β match equals 50: 50, and fluctuation range is 40: 60, and the content of crystal boundary phase YAG is 9% batching of principal crystalline phase weight;

(2) in ball grinding cylinder, be dispersion medium with the dehydrated alcohol, Si ₃N ₄Ball is that ball-milling medium mixed 24 hours, and oven dry is sieved, at 20MPa uniaxial tension compacted under, 200MPa cold isostatic compaction then;

(3) biscuit is at 1800 ℃ of 1 normal atmosphere N ₂The pressureless sintering insulation is 2 hours under the air-flow, and burying powder is Si ₃N ₄: AlN: BN=6: 3: 1 (wt%) or depressing under 1900-2000 ℃ of temperature insulation 1.5-3.0 hour at the high nitrogen of 1.5MPa again after the pressureless sintering;

(4) sample burns till the back in 1350 ℃ of logical N ₂Following 24 hours crystallization of condition are handled.